This invention relates to fitted sheets, and specifically to adjustable fitted sheets which are maintained in position primarily by portions of the sheet bearing against the sides and bottom of the mattress rather than against the corners of the mattress.
While this invention will be described primarily in connection with mattresses, and specifically spring and water bed mattresses, it will be understood that the sheet of this invention may be employed with various other types of cushions, such as pillows, sofa cushions and the like.
The normal unfitted or flat bed sheet, when used as the bottom sheet to cover a spring bed mattress, has many advantages in that it is adaptable to various size mattresses, may be positioned on the mattress in any of four directions, and may be installed on the mattress one side at a time without the necessity of lifting any portion of the mattress since the sheet edges may be merely folded or tucked in between the mattress and the springs. This later advantage is especially useful in hospitals where it is undesirable to discomfort the patient by lifting the corners and edges of the mattress, such as is necessary with the common contoured sheet. Flat bed sheets, however, are easily pulled out of position during the normal tossing and turning of a person sleeping on a bed. Such sheets consequently become wrinkled after a short period of time creating discomfort and, in hospital situations, causing bed sores.
The contoured bed sheets seek to overcome some of the problems of the flat sheet by elastic sewn around the top and bottom of the sheet and extending around all four corners. In order to install a contoured bed sheet on a spring mattress, three corners of the sheet are normally fitted around the first three mattress corners and the fourth corner of the mattress is then lifted to a substantial height in order to place the fourth corner of the sheet around the fourth mattress corner. Upon allowing the mattress to resume its original position, the contoured sheet is stretched tight across the top of the mattress and also at the corners, thus maintaining the sheet in a stretched or taut position for the normal period of time between washings. The contoured sheet has various disadvantages, however, since the tension created by the dimensions of the sheet and the elastic accelerates sheet wear to such an extent that the corners of the sheet frequently rip and the elastic wears out and shrinks before the normal life of the sheet fabric. In addition, the necessity for lifting at least one corner of the mattress to a considerable height when installing the sheet makes the contoured sheet particularly unsatisfactory for use in hospitals and the like. Furthermore, tension created across the top of the mattress by a contoured sheet diminishes the full capacity of the mattress. For example, some mattresses are constructed with an abundance of coil springs in order to allow the mattress to conform to the body contour of the person sleeping on the mattress. If a contoured sheeet is installed on such a mattress, the mattress will be placed under tension which tends to curl the corners and edges of the mattress upwardly and inwardly and to create stresses in the mattress which its designers did not intend. Such a prestressed mattress will not operate as intended and will thus deprive its owners of some of the benefits for which it was purchased. Such contoured sheets are also extremely awkward to fold and store due to the permanently crimped corners and the action of the elastic.
Water bed mattresses have presented a particular problem to the bedding industry. These mattresses are a generally rectangular rubber or plastic container with a substantially rounded nose around the sides and at the corners instead of square sides and corners. When such a mattress is filled with water, it generally raises to a height of about 10 inches. A normal fitted sheet is extremely unsatsifactory as the bottom sheet on a water bed mattress since it will be pulled loose from underneath the mattress in an extremely short period of time by displaced water pushing outwardly towards the mattress corners when a person sits or lies on the water bed. This displaced water hits against the corners of the mattress while at the same time the top surface of the mattress is placed under tension which tends to raise the corners of the mattress. Concurrently, the overlying sheet is placed under tension by the person sitting or lying on the bed. These stresses combined with the raised mattress corners eventually result in either tearing the corners or quickly loosening the sheet or both.
In an attempt to solve this problem, regular contoured sheets have been modified to provide deeper corners or pockets to accommodate water bed mattresses which are approximately 10 inches high, whereas regular spring mattresses are only about seven inches high. These contoured sheets have not solved the problem, however, since if they do remain in place on the mattress corners, the pressure against the sheet corners by the displaced water action described above causes the sheet corners to tear after a very short period of time. In any event, the sheet corners usually come loose from the mattress corners and thus these sheets continue to possess both disadvantages, that is, the sheet corners are subjected to stress until the sheet corners tear or come loose or both.
The top sheet commonly sold with contoured water bed bottom sheets is sewn to the foot of the contoured sheet, thus forming an expensive combination which must be washed, folded and stored together. In addition, since the bottom contoured sheet usually wears out extremely quickly, and certainly before the normal life of the sheet fabric, both the top and bottom sheet are rendered inoperative at an early stage.
The present invention overcomes the disadvantages of the prior art flat and contoured sheets by providing a fitted bottom sheet which has adjustable corners securely retained over the mattress corners while at the same time eliminating stress against the sheet corners and across the top sleeping panel of the sheet which might detract from the operability of the mattress. In its application to water beds, the bottom fitted sheet of this invention provides an aperture at each corner through which a portion of the water bed corners protrude so that the stresses transmitted to the water bed mattress corners by activity upon the mattress is not transferred to the sheet corners. Furthermore, the corners of this sheet are adjustable to accommodate various mattress dimensions while at the same time the sheets may be folded relatively flat for easy packaging and storage. In addition, these sheets are easily installed by merely folding portions of the sheet underneath the mattress without the necessity of raising the mattress to a substantial height, thus rendering this sheet particularly suitable for use in hospitals and the like.
Due to the lack of tension at the corners and across the top of the sheet of this invention, this sheet will not rip or tear during use so that the full life of the sheet material may be enjoyed. The adjustability of this sheet provides an actual reduction in the amount of material and number of sheet sizes required to fit the different size mattresses presently on the market. For example, a normal flat queen size sheet, when constructed in accordance with the teachings of this invention, will fit a water bed mattress, an eastern king size mattress, and the western king size mattress. A normal flat double bed size sheet, when constructed in accordance with the teachings of the invention, will fit a queen size mattress, a double bed size mattress and a sofa or hide-a-bed mattress. A flat twin size sheet, when constructed in accordance with the teachings of this invention, will fit all twin bed size mattresses from 36 to 39 inches in width. Such a reduction in the number of sheets and the size of the sheets required to fit the mattresses on the market will result in a great savings in both material and fabrication costs.